We have a real-life “Planet of the Apes” scenario in Northern Ireland as zookeepers say a troop of chimpanzees used fallen branches to construct a ladder for a daring escape last week.

The Associated Press reports “Zookeeper Alyn Cairns said trees in the chimps’ enclosure had been weakened by recent storms, allowing the animals to break them and fashion a ladder to escape. He told the BBC ‘they’re intelligent primates and know they’re not supposed to be out of their enclosure, so got back in themselves.'”

The video provided by The Guardian was taken by locals visiting the zoo. One attendee told the British paper that she was terrified but chose to remain calm.

“I was petrified, obviously, having the kids, and I tried not to show fear but inside I was a bit like: what happens if it attacks us or tries to take the kids or runs over?” Danielle Monoghan told the media.